Morphology and mapping analysis of rice (Oryza sativa L.) clustered spikelets (Cl) mutant

The rice clustered spikelets (Cl) mutant exhib-its a phenotype that most of branch apical have 2-3 spikelets clustered together. SEM (scanning electron microscope) ob-servation suggested that the Cl gene controlled branch apical development, and influenced the terminal spikelets elonga-tion. The spikelet number was reduced in mutant, indicating that Cl may also have an effect on spikelet number. To map Cl locus, two F2 mapping populations derived from the crosses between the Cl and ZhongHua11, and Cl and ZheFu802 were constructed, respectively. The Cl locus was roughly mapped between two CAPS markers, CK0214 and SS0324. A further fine mapping analysis showed that the Cl locus was mapped between makers R0674E and Cl2560, with genetic distances of 0.2 and 2.1 cM, respectively. Then we found a PAC contig spanning Cl locus, the region was delim-ited to 196 kb. This result was useful for cloning of the Cl gene. Allelism test demonstrated that Cl was allelic to Cl2, another rice clustered spikelets mutant.